The Experts below are selected from a list of 813 Experts worldwide ranked by ideXlab platform
Anthony Paul Roskilly - One of the best experts on this subject based on the ideXlab platform.
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a study and comparison of frictional losses in Free Piston engine and crankshaft Engines
Applied Thermal Engineering, 2018Co-Authors: Oru Jia, Andrew Smallbone, R Mikalse, Anthony Paul RoskillyAbstract:Abstract Friction work in Free-Piston Engines is expected to be lower than in crankshaft Engines due to the elimination of the crank mechanism. In this paper, friction mechanisms were reviewed and compared between a Free-Piston and crankshaft engine of similar size. The main friction mechanisms were identified to be the Piston assembly including Piston rings and Piston skirt, valve train system, the crank and bearing system for the CSE, and the linear electric generator for the FPE. The frictional loss of each friction mechanism was estimated and discussed. A Stribeck diagram was used to simulate the Piston ring friction during hydrodynamic lubrication, mixed lubrication, and boundary condition. It is found that the FPE doesn’t show advantage on Piston ring friction force over the CSE, and the frictional loss from the Piston ring is even higher. While the elimination of the crankshaft system reduces the frictional loss of the FPE, and the total friction loss of the FPE is nearly half of the CSE.
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design and simulation of a two or four stroke Free Piston engine generator for range extender applications
Energy Conversion and Management, 2016Co-Authors: Andrew Smallbone, Huihua Feng, Anthony Paul RoskillyAbstract:Abstract Free-Piston Engines (FPEs) are known to have a greater thermal efficiency (40–50%) than an equivalent and more conventional four-stroke reciprocating Engines (30–40%). Modern FPEs are proposed for the generation of electric and hydraulic power, with a potential application in hybrid electric vehicles. The numerous FPE configurations considered to date have almost exclusively operated using a two-stroke thermodynamic cycle to improve the thermal efficiency, however it is well known that the application of two-stoke cycles can be limited by noise and exhaust gas emissions constraints. In this article, a numerical model is used to investigate the techno-feasibility of operating Newcastle University’s FPE prototype using a two- or four-stroke thermodynamic cycle. If operated as a four-stroke cycle, the linear generator must be used as both a motor and a generator resulting in a more irregular Piston motion compared to corresponding operating in a two-stroke cycle. In four-stroke cycles, almost half the indicated power is consumed in overcoming the pumping losses of the motoring process. Whilst the heat release process is appears to be closer to a constant volume process when operated on two-stroke engine cycle, the peak cylinder pressure and compression ratio proved lower. In addition, a narrower power range is reported for a four-stroke cycle despite a corresponding higher thermal efficiency.
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The control of a Free-Piston engine generator. Part 1: fundamental analyses ⋆
2015Co-Authors: R Mikalsen, Anthony Paul RoskillyAbstract:Free-Piston Engines are under investigation by a number of research groups due to potential fuel efficiency and exhaust emissions advantages over conventional technology. The main challenge with such Engines is the control of the Piston motion, and this has not yet been fully resolved for all types of Free-Piston Engines. This paper discusses the basic features of a single Piston Free-Piston engine generator under development at Newcastle University and investigates engine control issues using a full-cycle simulation model. Control variables and disturbances are identified, and a control strategy is proposed. It is found that the control of the Free-Piston engine is a challenge, but that the proposed control strategy is feasible. Engine speed control does, however, represent a challenge in the current design
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The control of a Free-Piston engine generator. Part 2: engine dynamics and Piston motion control ⋆
2015Co-Authors: R Mikalsen, Anthony Paul RoskillyAbstract:Free-Piston Engines are under investigation by a number of research groups due to potential fuel efficiency and exhaust emissions advantages over conventional technology. The main challenge with such Engines is the control of the Piston motion, and this has not yet been fully resolved for all types of Free-Piston Engines. This paper builds on the fundamental investigations presented in the accompanying paper and investigates the dynamics of the engine and the feasibility of classical control approaches. The response of the engine to rapid load changes are investigated using decentralised PID, PDF and disturbance feedforward. It is found that the engine is sensitive to rapid load changes but that in constant power applications standard control techniques provide satisfactory performance. The influence of cycle-to-cycle variations in the combustion process are investigated, but not found to be critical for engine operation
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The design and simulation of a two-stroke Free-Piston compression ignition engine for electrical power generation.
2015Co-Authors: R Mikalsen, Anthony Paul RoskillyAbstract:Free-Piston Engines are under investigation by a number of research groups worldwide due to their potential ad-vantages in terms of fuel efficiency and engine emissions. Some prototypes have emerged, mainly aimed for vehicle propulsion, and have reported favourable performance compared to conventional technology. This paper describes the design of a modular compression ignition Free-Piston engine generator, applicable to electric power generation in large-scale systems. The development of a full-cycle engine simulation model is described, and extensive simulation results are presented, giving insight into engine operating characteristics and performance. The operating character-istics of the Free-Piston engine was found to differ significantly from those of conventional Engines, giving potential advantages in terms of fuel efficiency and emissions formation due to fast power stroke expansion. Effects of varying engine stroke length and compression ratio were not found to give any large advantages. Key words: Free-Piston, two-stroke, diesel, linear combustion engine generator 1
R Mikalsen - One of the best experts on this subject based on the ideXlab platform.
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The control of a Free-Piston engine generator. Part 2: engine dynamics and Piston motion control ⋆
2015Co-Authors: R Mikalsen, Anthony Paul RoskillyAbstract:Free-Piston Engines are under investigation by a number of research groups due to potential fuel efficiency and exhaust emissions advantages over conventional technology. The main challenge with such Engines is the control of the Piston motion, and this has not yet been fully resolved for all types of Free-Piston Engines. This paper builds on the fundamental investigations presented in the accompanying paper and investigates the dynamics of the engine and the feasibility of classical control approaches. The response of the engine to rapid load changes are investigated using decentralised PID, PDF and disturbance feedforward. It is found that the engine is sensitive to rapid load changes but that in constant power applications standard control techniques provide satisfactory performance. The influence of cycle-to-cycle variations in the combustion process are investigated, but not found to be critical for engine operation
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The control of a Free-Piston engine generator. Part 1: fundamental analyses ⋆
2015Co-Authors: R Mikalsen, Anthony Paul RoskillyAbstract:Free-Piston Engines are under investigation by a number of research groups due to potential fuel efficiency and exhaust emissions advantages over conventional technology. The main challenge with such Engines is the control of the Piston motion, and this has not yet been fully resolved for all types of Free-Piston Engines. This paper discusses the basic features of a single Piston Free-Piston engine generator under development at Newcastle University and investigates engine control issues using a full-cycle simulation model. Control variables and disturbances are identified, and a control strategy is proposed. It is found that the control of the Free-Piston engine is a challenge, but that the proposed control strategy is feasible. Engine speed control does, however, represent a challenge in the current design
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The design and simulation of a two-stroke Free-Piston compression ignition engine for electrical power generation.
2015Co-Authors: R Mikalsen, Anthony Paul RoskillyAbstract:Free-Piston Engines are under investigation by a number of research groups worldwide due to their potential ad-vantages in terms of fuel efficiency and engine emissions. Some prototypes have emerged, mainly aimed for vehicle propulsion, and have reported favourable performance compared to conventional technology. This paper describes the design of a modular compression ignition Free-Piston engine generator, applicable to electric power generation in large-scale systems. The development of a full-cycle engine simulation model is described, and extensive simulation results are presented, giving insight into engine operating characteristics and performance. The operating character-istics of the Free-Piston engine was found to differ significantly from those of conventional Engines, giving potential advantages in terms of fuel efficiency and emissions formation due to fast power stroke expansion. Effects of varying engine stroke length and compression ratio were not found to give any large advantages. Key words: Free-Piston, two-stroke, diesel, linear combustion engine generator 1
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recent commercial Free Piston engine developments for automotive applications
Applied Thermal Engineering, 2015Co-Authors: R Mikalsen, Razali M Hanipah, Anthony Paul RoskillyAbstract:Free-Piston Engines have been under extensive investigation in recent years, however have not yet seen commercial success in modern applications. This paper reviews some of the recently reported commercial developments in Free-Piston engine systems particularly aimed for use in hybrid electric vehicle powertrains and discuss these in light of published research. By looking at recent publications, and in particular patent documents, from major industrial players, insight into the less widely reported commercial research efforts on Free-Piston Engines is obtained. Further, these publications provide a useful indication as to what these developers see as the main technical challenges for this technology.
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Coupled dynamic–multidimensional modelling of Free-Piston engine combustion. ⋆
2014Co-Authors: R Mikalsen, Anthony Paul RoskillyAbstract:Free-Piston Engines are under investigation by a number of research groups worldwide, as an alternative to conven-tional technology in applications such as electric and hydraulic power generation. The Piston dynamics of the Free-Piston engine differ significantly from those of conventional Engines, and this may influence in-cylinder gas motion, combustion and emissions formation. Due to the complex interaction between mechanics and thermodynamics, the modelling of Free-Piston Engines is not straight-forward. This paper presents a novel approach to the modelling of Free-Piston Engines through the introduction of solution-dependent mesh motion in an engine CFD code. The partic-ular features of Free-Piston Engines are discussed, and the model for engine dynamics implemented in the CFD code is described. Finally, the coupled solver is demonstrated through the modelling of a spark ignited Free-Piston engine generator. Key words: Free-Piston engine, dynamic modelling, CFD 1
Andrew Smallbone - One of the best experts on this subject based on the ideXlab platform.
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a study and comparison of frictional losses in Free Piston engine and crankshaft Engines
Applied Thermal Engineering, 2018Co-Authors: Oru Jia, Andrew Smallbone, R Mikalse, Anthony Paul RoskillyAbstract:Abstract Friction work in Free-Piston Engines is expected to be lower than in crankshaft Engines due to the elimination of the crank mechanism. In this paper, friction mechanisms were reviewed and compared between a Free-Piston and crankshaft engine of similar size. The main friction mechanisms were identified to be the Piston assembly including Piston rings and Piston skirt, valve train system, the crank and bearing system for the CSE, and the linear electric generator for the FPE. The frictional loss of each friction mechanism was estimated and discussed. A Stribeck diagram was used to simulate the Piston ring friction during hydrodynamic lubrication, mixed lubrication, and boundary condition. It is found that the FPE doesn’t show advantage on Piston ring friction force over the CSE, and the frictional loss from the Piston ring is even higher. While the elimination of the crankshaft system reduces the frictional loss of the FPE, and the total friction loss of the FPE is nearly half of the CSE.
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design and simulation of a two or four stroke Free Piston engine generator for range extender applications
Energy Conversion and Management, 2016Co-Authors: Andrew Smallbone, Huihua Feng, Anthony Paul RoskillyAbstract:Abstract Free-Piston Engines (FPEs) are known to have a greater thermal efficiency (40–50%) than an equivalent and more conventional four-stroke reciprocating Engines (30–40%). Modern FPEs are proposed for the generation of electric and hydraulic power, with a potential application in hybrid electric vehicles. The numerous FPE configurations considered to date have almost exclusively operated using a two-stroke thermodynamic cycle to improve the thermal efficiency, however it is well known that the application of two-stoke cycles can be limited by noise and exhaust gas emissions constraints. In this article, a numerical model is used to investigate the techno-feasibility of operating Newcastle University’s FPE prototype using a two- or four-stroke thermodynamic cycle. If operated as a four-stroke cycle, the linear generator must be used as both a motor and a generator resulting in a more irregular Piston motion compared to corresponding operating in a two-stroke cycle. In four-stroke cycles, almost half the indicated power is consumed in overcoming the pumping losses of the motoring process. Whilst the heat release process is appears to be closer to a constant volume process when operated on two-stroke engine cycle, the peak cylinder pressure and compression ratio proved lower. In addition, a narrower power range is reported for a four-stroke cycle despite a corresponding higher thermal efficiency.
Mikalsen Rikard - One of the best experts on this subject based on the ideXlab platform.
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An Investigation into the Free-Piston Engine Concept and its Potential for High Efficiency and Low Emissions Power Generation
2008Co-Authors: Mikalsen RikardAbstract:An investigation into the feasibility of the Free-Piston engine concept and its potential for high. efficiency and low emissions power generation has been conducted using computational modelling and simulation. A thorough background study and literature review was carried out covering previously reported experience with Free-Piston Engines, particular features of this technology, and potential advantages and challenges associated with their design. A single Piston Free-Piston engine generator was proposed as a result of the background study and a design strategy for this engine configuration was formulated. Detailed simulation models for the Free-Piston engine were developed and extensive simulation studies conducted to investigate the performance and operating characteristics of such an engine. Engine performance indicators, such as fuel efficiency, power to weight ratio, and exhaust gas emissions formation, were studied along with engine operational control issues. The results were directly compared to those of equivalent conventional crankshaft Engines in order to investigate potential differences in engine performance. It was found that the Free-Piston engine has potential advantages over conventional technology in the areas of mechanical efficiency, exhaust gas emissions formation, and operational flexibility. The main challenge lies within the area of Piston motion control and further research into engine control issues are required. A more detailed study of engine emissions formation is also recommended in order to fully understand the influence of the particular operating characteristics of the Free-Piston configuration on engine performance.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
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An investigation into the Free-Piston engine concept and its potential for high efficiency and low emissions power generation
Newcastle University, 2008Co-Authors: Mikalsen RikardAbstract:PhD ThesisAn investigation into the feasibility of the Free-Piston engine concept and its potential for high efficiency and low emissions power generation has been conducted using computational modelling and simulation. A thorough background study and literature review was carried out covering previously reported experience with Free-Piston Engines, particular features of this technology, and potential advantages and challenges associated with their design. A single Piston Free-Piston engine generator was proposed as a result of the background study and a design strategy for this engine configuration was formulated. Detailed simulation models for the Free-Piston engine were developed and extensive simulation studies conducted to investigate the performance and operating characteristics of such an engine. Engine performance indicators, such as fuel efficiency, power to weight ratio, and exhaust gas emissions formation, were studied along with engine operational control issues. The results were directly compared to those of equivalent conventional crankshaft Engines in order to investigate potential differences in engine performance. It was found that the Free-Piston engine has potential advantages over conventional technology in the areas of mechanical efficiency, exhaust gas emissions formation, and operational flexibility. The main challenge lies within the area of Piston motion control and further research into engine control issues are required. A more detailed study of engine emissions formation is also recommended in order to fully understand the influence of the particular operating characteristics of the Free-Piston configuration on engine performance
Zhenfeng Zhao - One of the best experts on this subject based on the ideXlab platform.
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Research on the Operating Characteristics of Hydraulic Free-Piston Engines: A Systematic Review and Meta-Analysis
'MDPI AG', 2021Co-Authors: Shuanlu Zhang, Zhenfeng Zhao, Yifang WangAbstract:The hydraulic Free-Piston engine (HFPE) is a kind of hybrid-powered machine which combines the reciprocating Piston-type internal combustion engine and the plunger pump as a whole. In recent years, the HFPE has been investigated by a number of research groups worldwide due to its potential advantages of high efficiency, energy savings, reduced emissions and multi-fuel operation. Therefore, our study aimed to assess the operating characteristics, core questions and research progress of HFPEs via a systematic review and meta-analysis. We included operational control, starting characteristics, misfire characteristics, in-cylinder working processes and operating stability. We conducted the literature search using electronic databases. The research on HFPEs has mainly concentrated on four kinds of Free-Piston engine, according to Piston arrangement form: single Piston, dual Pistons, opposed Pistons and four-cylinder complex configuration. HFPE research in China is mainly conducted in Zhejiang University, Tianjin University, Jilin University and the Beijing Institute of Technology. In addition, in China, research has mainly focused on the in-cylinder combustion process while a Piston is Free by considering in-cylinder combustion machinery and Piston dynamics. Regarding future research, it is very important that we solve the instabilities brought about by chance fluctuations in the combustion process, which will involve the hydraulic system’s efficiency, the cyclical variation, the method of predicting instability and the recovery after instability
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thermodynamic and energy saving benefits of hydraulic Free Piston Engines
Energy, 2016Co-Authors: Zhenfeng Zhao, Shan Wang, Shuanlu Zhang, Fujun ZhangAbstract:The hydraulic Free-Piston engine integrates the internal combustion engine with a hydraulic pump. The Piston of an HFPE is not connected to the crankshaft and the Piston movement is determined by the forces that act upon it. These features optimize combustion and make higher power density and efficiency increase. In this paper, a detailed thermodynamic and energy saving analysis is performed to demonstrate the fundamental efficiency advantage of an HFPE. The thermodynamic results show that the combustion process can be optimized to an ideal engine cycle. The experimental results show that the HFPE combustion process is a nearly constant-volume process; the efficiency is approximately 50%; the Piston displacement and velocity curves for a cycle are the same at any frequency, even at a 1.25 Hz. The maximum velocities are of the same value at high or low frequencies. Similarly, pump output flow is not influenced by frequency. The independent cyclic characteristics of HFPE determine that it should work in higher frequencies when the vehicle runs in Japanese 10–15 road conditions. It indicates that a higher working frequency will lead to the starting frequency of HFPE, and a lower frequency will decrease the pressurized pressure of the hydraulic accumulator.
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an experimental study of the cycle stability of hydraulic Free Piston Engines
Applied Thermal Engineering, 2013Co-Authors: Zhenfeng Zhao, Fujun Zhang, Ying Huang, Changlu ZhaoAbstract:Abstract The Piston motion of hydraulic Free-Piston engine (HFPE) without being restricted as that of conventional crankshaft engine (CE), leads to the cyclic variations, which raises concerns over engine cycle stability. It is therefore necessary to investigate the cycle-to-cycle variations in the Piston dynamics and cycle stability of HFPEs. For this purpose, we conducted and evaluated an experimental study of a prototype HFPE. The experimental results indicate that the HFPE was in steady state when it ran at the maximum range of the cyclic variations in the Piston dynamic parameters. In addition, variations in the top dead center (TDC) position, bottom dead center (BDC) position, starting Piston position and compression ratio were investigated. In this prototype, the maximum variation in the TDC position relative to the total stroke was 1.2%; the starting position of the Piston oscillated between 11 and 19 mm, the maximum variation relative to the total stroke was 2.9%; the BDC variation ranged from 4.5 to 13 mm; and the maximum relative variation in the BDC position to the total stroke was 2.7%.
